Blocking or mounting lenses for grinding.



Y No. 689,933.

BLOCKING 0B MOUNTINQ LENSES FOB GRINDING.

(No Model.)

' WITNESSES:

J. K. UNDERWODEL.

(Application md Dec. 22, 1900.

Patcnt'ad Dec. 3|, l90l.

3 Sheets-Sheet l.

Johnlilrndwmwww,

ATTORNEYS.

J. K. UNDERWOOD.

Patented Dsc. 3|, l90l.

BLOCKING 0R MOUNTING LENSES FOR GRINDING.

(No lollel.)

may 6.

WITNESSES :A mmun npa'mc. an, 1900 I than-Shut 2.

INVENTOR J. K. UNDERWOOD.

BLOCKING 0R MOUNTING LENSES FOR GRINDING.

(No Model.)

(Apphenion fllgd Dec. 22, 1900.)

Patented Dec. 3|, l90l.

3 Sheets-Sheet 3.

bii 7 N7- z i INVENTOR WITNESS Run J5, v J

ATTORNEYS UNITED STATES P TE T OFFICE.

JOIIN K. UNDERWOOD, or NFWARK, NEW JERSEY, ASSIGNOR TO THE SPENCER OPTICAL MANUFACTURING COMPANY, A CpRPonA'rIoN 0F NEXV JERSEY.

BLOCKING 0R MOUNTING LENSES FoR camomo.

srnczrrcarron r fining part of Letters Patent No. 689,933, dated December 31, 1901.

To all whom it may concern:

Be it known that I, JOHN K. UNDERWOOD, acitizen of the United States, residing at Newark, in the county of Essex and State of New Jersey, have invented certain new and 'useful Improvements inBlocking or Mounting Lenses for Grinding; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being bad to the accompanyingdrawin gs, and to letters of reference marked thereon, which form a part of this specification.

This invent-ion relates to the art of blocking or mounting lenses preliminary to grinding the surfaces of the said lenses. The method heretofore generally followed in lensgrinding factories has been to cast in a mold a form consisting of a composition of rosin and pitch, the said elements of the composition being proportioned to meet varying conditions and requirements of temperatnre,&c.

In said prior methods the mold is first properly shaped interiorly to such a curved plane or other form as will bring the plastic matter into shape to hold the glasses at positions necessary to secure the desired focus, when the lenses are ground and polished, and the said mold is filled more or less completely .with the composition, and an iron block, which has been previously heated so that it will melt the said composition or render the same plastic and effect an adhesion of said composition of said block, is then inserted in the mold. When sufficiently cool, the block is withdrawn, bringing the form of pitchy composition with it. A number of lenses are then heated and placed on the rounded or other shaped surface of the form and pressed against it by the operator or workman by means of what is known as a blocking-pin. The depth to which each glass or lens is pressed into the pitch depends on the skill of the operator. Even with great skill there has been an irregularity in depth of the sitting of the several lenses or glasses on the form and in the arrangement of the lens with reference to the curved surface, so that the lenses have greatly varied both in thickness Application filed December 22, 190i). Serial No. 40.734. (Remodel) and in the location of their focuses, as will be apparent. In my improved method or 'process of blocking the lenses I avoid these variations and secure a more uniform product and reduce the cost of manufacture.

Referring to the accompanying drawings, in which like letters of reference indicate corresponding parts in each of the several views, Figure l is a plan of a concave mold for blocking lenses tobe ground convexly; and Fig. 2 is a section of the same, taken on line 0:, Fig. 1. Fig. 3 is a side elevation of the block having lenses applied thereto ready for grinding; and Fig. 4 shows in section the mold, block, lenses and adhesive matter in position preliminary to withdrawing the block, 8.10., from the mold. Fig. 5 is' a plan showing a, convex mold having recesses for the lenses or lens-glasses and adapted to force said lens-glasses into the pitch of the block in the operation of making concave lenses. Fig. (i is a section on line as, Fig. 5. Fig. 7 is a plan of the concave block adapted to be used with said convex mold. Fig. 8 is a plan showing said block arranged in connection .with a .mold; and Fig. 9 is a. section online 1 Fig. 8. Fig. 10 is a plan, and Fig. 11 is a section on line 2, Fig. '10, of a recessed mold for use in seating glasses for convex cylindrical grinding. Fig. 12 is a section of a block to cooperate with the last said mold. Figs. 13 and 14 are respectively the mold and block for concave cylindrical grinding. Fig. 15 is a plan, and Fig. 16 is a section, as on line zf, Fig. 15, of a flat mold recessed to receive glasses in the manufacture of prismatic lenses. Fig. 17 is a block to receive the seated glasses from said flat mold preliminary togrinding. Fig. 18 shows the relation of said mold, block, pitch, and lenses in the second blocking operation after the lenses have been ground on one side, and Fig. 19 shows the lenses seated on the block ready to be ground on the second side to complete the form of a prism.

In said drawings, it indicates the mold; b,

the block; c, the waxen or pitchy composition,

and d the lenses applied to the block by means of the said composition.

In my improved system or process of blocking or mounting the lenses for grinding the mold ais made of iron-or other suitable metal,

5 cure the desired proper curvature of the composition necessary for holding the lenses in.

the proper relative position for grinding to a desired focus or thickness. For grinding to other than convex surfaces the mold is made I0 of other suitable shapes, as will'be hereinafter more fully described. The said concave or other shaped surface is provided with a collection of shallow lens-recesses a of a depth and outline adapted to receive the lenses and hold the same exactlyin such proper relative positions that when withdrawn from the mold with the block said lenses will be in true and exact position for grinding to a u niform focus. The glass pieces or lenses after being heated are quickly placed in the recesses or recep- -'tacles a. therefor and automatically assume their exact relative positions without any skill or care on the part of the operator. A heated composition of pitch and wax or other 2 5 suitable adhesive matter is then poured-into the mold, the heated block b is inserted into the mass, as indicated in Fig. 4, and the whole -is allowed to cool, the plastic or adhesive matter becoming hard and serving as a firm backing for the glasses. The block his then withdrawn, carrying the pitchy composition a on its outside and thelenses or glasses embedded therein, said glasses being disposed exactly in their proper relative positions and at uniform'depths in the pitchy mass ready for grinding in'the ordinary grinding-shell.

By my improved method and means thus described of mounting the glasses or lenses I avoid the loss of time required for carefully 40 pressing down the individual lenses.

To enable the lenses to be withdrawn from the concave mold with the plastic composition upon the block, I bevel the upper walls of the recesses, as indicated at f in Figs. 1

5 and 2.

The mold and block shown in Figs. 1 to 4 are for use in grinding convex lens-surfaces. When I apply my invention to the production or manufacture of concaved lens-surfaces, I employ such forms of the parts as are shown in Figs. 5,6, 7 8, and 9, in which case the concave block b serves as a receptacle .for the pitch, while the convex mold a has the recessed surface, by means of which the lens-glasses are properly located preliminary to grinding. Said molda. has the glasses temporarily fastened into the said recesses by shellac or other adhesive material to hold the said glasses in place when the mold is inverted to be forced into theblock b, and after fasten'in g the glasses in said recesses the mold is forced into the warm adhesive matter within the block, as shown in Fig. 9, After the convex mold a with its applied glasses, has been inserted into the block b, having the semifluid pitch,

and has been pressed into proper relative position and after the said pitch has been cooled lac by which the glasses are fastened to said mold being insufiicient in strength to overcome the adhesive character of the pitch. The glasses are now found projecting a little from the concave bed of pitch and are thus adapted to receive a convex grinding member, which is inserted and 0 erated in any suitgrinding.

Where the invention is employed for grindshown in Figs. 10, 11, 12, 13, and 14, the construction shown in Figs. l0, l1, and 12 being 'employed in blocking for grinding the conf vex side of cylind rical lenses and that shown in Figs. 13 and 14 illustrating the mold and block employed in blocking for the concave ment of a cylinder, as indicated in Fig. 11, and is provided with recesses to receive the sition while the pitch is being applied and preliminary to stripping the glasses from the and the glasses are applied within the remeans of shellac or the like while the mold is inverted for insertion into the concave block b containing the pitch, as has been before described in substance. In this case the glasses are disposed in a cylindrical relation and the. grinding parts operate substantially as described in a copending application.

srinding p sms.

shown in Figs. 15, 16, 17, 18, and 19, where are formedin a fiat mold a, the bottoms of the recesses being inclined, so that the glasses will be somewhat set up at an incline, as shown in Fig. 16. In this case the viscous pitch is poured upon the center of the mold and a flat block b is applied to the top therecooling the block is remgved, as usuahand the glasses are drawn away from the mold therewith and project from the surface of the pitch, as shown in Fig. 17. Tl 1e p rpjecting any grinding process, preferably by'the precess described in my copending application above referred to, and after the grinding is completed the glasses are removed and again first used, the ungronnd sides being inserted in the recesses of the mold and the smaller edge of each partially-formed prism being placed in-the deeper part of a recess. The pitch is then again applied and the block I) pressed upon the same, so that again the pitch and the g asses adhere to said block and are prism is formed. as indicated in Fig. 19.

and hardened the mold is withdrawn,the sheling cylindrical lenses, I use the construction the block 12 brought to bear upon the pitch cesses of the convex mold a and held by ylhen I, desire to employ my ipvgntionin em'pldi'a construction the recesses (1, adapted to receive the glasses,

inserted in the recesses of the same mold a withdrawn from the mold together, and thesecond side is then ground, so that a com plete 7*; able manner to effect he desired concave I side. In these drawings the mold 03 is a 'seg- T glasses and hold them in proper relative posaid mold. In Fig. 13 the reverse is shown, I

of, and under pressure the pitch flattens out and overflows the sides to some extent. Upon portions of the glasses are then ground by 2 dim,

Having thus described the invention, what I claim as new is- 1. The process herein described of blocking lenses for grinding, consisting essentially in arranging the lenses within recesses formed,

at predetermined positions with respect to the axis of the mold, the said lenses projecting out from said recesses a limited distance, applying plastic matter to said lenses, the plastic matter extending across the broad exposed surfaces of the lenses and at the edges thereof, inserting a block in said plastic matter, and causing the said lenses to adhere to ,Said block and withdrawing the block from the mold together with the said plastic matter and lenses, the latter being embedded within said plastic matter and only partially projecting out therefrom, thesaid lenses thus being exactly seated upon said block at predetcrmined positions about the axial center of JOHN K. UN DERVVOOD.

\Vitnesses:

CHARLES II. PELL, (3. l3. PITNEY. 

